How do you decide your career choice?

That's fine! Especially if you're still in high school—the first two years of college are actually set up to help you figure out what you want to do. Right now, just explore things. Spend the time you have finding out what you enjoy or are interested in doing, and then you can figure out what kind of jobs you can get with that once you're in college and have a career services department to help you.

Like what @jcdenton said, the first two years of college really can be for figuring out what you want to do. Many places don't require you to commit to a major until after sophomore year. Chances are, many of the peers who you think have it figured out probably don't. They might have an idea of what they want to study but that could totally change by the time they go to college or while they're in college. It's actually REALLY common for people to change majors.

Just to give some anecdotal evidence, almost everyone I know in my family changed their majors at least once. My cousin is thinking of changing their major for a 3rd time I believe. Plus, I've known people who graduate with a specific major, but get a job in an unrelated field, and then end up loving that field. So even if you major in one thing it doesn't mean you'll HAVE to work in that major for the rest of your life. Try not to stress too much about it and I'm sure something will come to you.